1. Field of the Invention
The present invention relates to a docking station for an environmental monitoring instrument and the interaction between the docking station, the instrument and a service center.
2. Description of Related Art
Potentially dangerous gas mixtures (e.g. combustible gases, toxic gases, excessively high or low oxygen concentrations), noise levels, particulates etc. are found in many work place environments. These dangers are well known and monitoring instruments are available to detect a wide range of potential hazards. Monitoring instruments are also available for other applications including environmental monitoring, such as water quality (e.g. pH, dissolved oxygen, suspended solids, dissolved ions, clarity), pollution control (e.g. volatile organic compounds VOC""s, oxides of nitrogen, ozone, particulates etc.), indoor air quality (e.g. carbon dioxide, relative humidity, temperature), and quality of compressed air for a breathing apparatus (e.g. oxygen, carbon monoxide, carbon dioxide, relative humidity). These monitoring instruments typically contain one or more sensors, a signal processing means and output.
For many monitoring applications, if the concentration of the analyte or the magnitude of a physical parameter determined exceeds pre-determined limits, then the instrument may provide an alarm to warn nearby personnel, or it may activate other remedial actions. For example, the instrument may initiate actions such as increasing ventilation or diverting a drinking water stream if the water quality levels are outside of the allowed limits, until the problem is corrected.
Monitoring instruments for safety and environmental applications are broadly divided into two groups, portable instruments which are designed to be hand held or worn by the user, or can easily be transported from one location to another, and fixed instruments which are typically mounted in a fixed location and which provide monitoring at that location.
Monitoring instruments typically contain one or more sensors, which provide an electrical response that varies with the concentration of the analyte or with a parameter being measured. For each sensor, there is associated circuitry for driving the sensor, for measuring and displaying and/or recording the output and for activating visual, vibrational or audible alarms used to notify the user of the presence of a potentially hazardous condition.
Most instruments also contain a microprocessor or other controller and memory features that allow for more complex data analysis, such as industrial hygiene functions. Examples of industrial hygiene functions include calculating time weighted exposure limits, or recording the variation in exposure over time for later analysis. For many toxic substances, especially gases, the time-weighted exposure is as important as the short-term exposure concentration. For example, carbon monoxide has an Immediately Dangerous to Life and Health (IDLH) concentration of 1200 ppm; this corresponds to the maximum concentration of gas from which the average worker can escape without a respirator and without loss of life or irreversible health effects in less than thirty minutes. However, the time weighted average permissible exposure limit (TWA-PEL) to carbon monoxide is only 50 ppm (OSHA); this is the maximum exposure that the average worker can be exposed to for eight hours a day, forty hours a week, repetitively, without adverse effects (NIOSH Pocket Guide to Chemical Hazards, US Department of Health and Human Services, June 1997). Typically, an analytical instrument will store the exposure data for at least one eight-hour shift, and then the data is downloaded to a computer for record keeping and further analysis.
In locations where high concentrations of toxic gases or low concentrations of oxygen are expected, workers may be supplied with a breathable air supply from a compressed gas source. Usually these air supplies incorporate instruments which monitor for toxic and other gases (e.g. carbon monoxide), since if this air supply is contaminated (e.g. by malfunction of the compressor), then it could be very detrimental to the workers who depend on it.
In typical use, a monitoring instrument is calibrated prior to use, a laborious process. Using hazardous gas monitoring as an example, the sensor background outputs are initially set to zero for both toxic and combustible gases by exposure of the instrument to clean air or zero gas. Subsequently, the instrument is exposed to a test mixture, which contains one or more active components of known concentration to which the sensors respond. For calibrating gas sensors, the test mixture is a known concentration of the analyte gas in inert balance gas. For a pH measuring electrode, the calibration may be performed using one or more buffer solutions of known pH as the test mixture. Similarly, other types of sensors will require their own specific test mixtures for calibration. The output of the instrument being calibrated is then set to the known value of the test mixture for each sensor.
The calibration process will vary with each type of sensor and instrument, but all processes involve matching the output of the instrument to a known value, usually a test mixture. For most applications involving safety and environmental monitoring, detailed records of the calibration results are required. The calibration interval depends on the sensor type, the instrument design and on the specific environment in which the instrument is being used. Typically, electrochemical and catalytic gas sensors are calibrated monthly whereas infrared-based gas sensors are calibrated annually. However, there is considerable variation between manufacturers and even instrument models that use similar sensor technology.
Though most sensor technologies are very reliable, as required for safety and environmental applications, sensors do sometimes fail in service. Some sensors, such as galvanic oxygen sensors, are consumed during the oxygen detection reaction and so have a limited lifetime. Many sensors do not have a fixed service life and only fail when a problem develops or the sensor is damaged (e.g. contamination of a pH electrode).
Whereas calibration is usually only performed at fixed time intervals, for many safety and environmental applications it is common practice to xe2x80x9cbump testxe2x80x9d monitoring instruments to ensure that they are working correctly. The bump test typically involves application of a test mixture to the instrument for enough time to active the warming alarms or other modes of display that indicate that the instrument responded correctly. While the bump test procedure takes less time than a full calibration, it still requires the expense of both time and obtaining a test mixture of known composition.
One area of current development is in-situ diagnostic testing. These tests are performed automatically by the instrument, either with, or preferably without human intervention. Diagnostic methods have been developed for a variety of different sensor types. For example, electrode capacitance methods have been described by Jones in U.S. Pat. No. 5,202,637 and by Studer in U.S. Pat. No. 5,611,909 for electrochemical toxic gases sensors. Parker described a method for galvanic oxygen sensors in U.S. Pat. No. 5,405,512 and Wang et al described a diagnostic method for polarographic oxygen sensors in U.S. Pat. No. 5,558,752. A method for identifying a failing combustible gas sensor has been described by Tantram in U.S. Pat. No. 3,960,495. These diagnostic tests provide the means for evaluating whether critical instrument components, such as the gas sensors are working correctly. Ideally, the instrument, without human involvement, can perform these tests periodically and automatically, and if a component fails the test, then the user is alerted to the problem.
These diagnostic tests have many advantages, such as low cost and automatic operation without human intervention; however in most cases, the best method for testing a sensor is with the intended analyte. For example, a gas sensor should be tested by recording the response of the sensor upon exposing it to the intended analyte gas or a verified substitute. To this end, gas generators have been built into several monitoring instruments; for example, Finbow et al described in U.S. Pat. No. 5,668,302 an electrochemical sensor that incorporated an electrolysis gas-generating cell for bump testing the sensor. Dodgson described a similar device in published PCT application WO 98/25,139. It is likely that automatic diagnostic testing and in-situ test gas generation will become more prevalent in the future.
One of the newest developments in monitoring analytical equipment is the concept of a monitoring instrument docking station. This concept greatly simplifies the existing support necessary for the successful use of a monitoring instrument. The docking station contains a bay into which the monitoring instrument can be mounted, the bay providing means of communication with the instrument. This communication may be via a communications port, infrared link or any other method known in the art. The bay also contains means by which the test mixture can be delivered to the instrument, so that the instrument can be calibrated.
In a typical scenario, when the instrument is mounted into the bay on the docking station, there is bi-directional communication between the instrument and the docking station. This communication may include instrument identification (e.g. serial number) and the current instrument configuration (e.g. alarm levels, identity of installed sensors, software version). The instrument may also download industrial hygiene or data logging results, such as exposure over time etc., to the docking station. The docking station will then calibrate the instrument with the test mixture. In addition to applying the test mixture to the instrument, the docking station must communicate with the instrument that calibration is in progress, receive the resulting test data from the instrument. If the calibration is a success, the instrument is reset for use, and if the instrument fails to calibrate correctly, the user is alerted to the problem.
From the user""s standpoint, the use of a docking station greatly simplifies the calibration process. Thus, the user plugs the instrument into a bay on the docking station, and at a later time, when the instrument is retrieved, it is freshly calibrated and ready for use. All of the tedious calibration steps are automated and the record keeping of both the calibration and the hygiene/data logging functions are logged automatically on a personal computer associated with the docking station. The data obtained are available for later retrieval whenever needed.
Examples of currently available docking stations include the TIMxe2x80x94Total Instrument Manager from Mine Safety Appliances Co., Cranberry Township, Pa. 16066 and the IMSxe2x80x94Instrument Management System from Heath Consultants Inc. Houston Tex., 77061. The TIM system provides means to do automatic calibration of gas detection instruments and detection of some existing faults with the instrument. In addition, the system stores the gas exposure and other records locally on the attached computer for later retrieval.
While the introduction of these base-stations constitutes a major advance for users of monitoring instruments, they are still somewhat limited. The instrument performance tests, configuration information and the data logging results are local to the docking station. It is certainly possible for the data to be transmitted to other locations across a network or to more remote locations by standard means, but this requires an additional step and a knowledgeable operator. It also requires pre-planning of where to send the data. For example, if the data is needed at a particular location, the data must be sent to that location. A system whereby the data from a large number of docking stations is automatically sent to a central location, such as a service center would be very advantageous.
The IMS also uses docking stations, and the IMS can connect via a direct line modem to a central database to download gas exposure data, calibration data and diagnostic information. However, the IMS lacks any additional automated analysis of the data to provide a predictive diagnostic capability.
It is therefore an object of the invention to provide a docking station for environment monitoring instruments that enables automatic retrieval of information from the instrument, and both local and remote analysis of data from the instrument.
To achieve this and other objects, the invention provides a monitoring instrument docking station which can be connected to, or incorporates within, a computer, and one or more bays for interfacing with monitoring instruments. The docking station includes a bi-directional data port which can download information from and upload information to the monitoring instruments, and may also contain means to bump test or calibrate the monitoring instruments. The docking station may also be capable of recharging the instrument batteries, where applicable, and of performing diagnostic tests on the instrument to identify current or future problems or failure. The docking station also contains means to connect, via the Internet, direct telephone or wireless communication, to a service center, which can be located anywhere in the world. The service center maintains a database of the data received from many docking stations and the service center uses software to analyze the data to provide diagnostic data about the monitoring instruments and thus improve their reliability. This analytical software may be based on neural networks, principle component analysis, and other mathematical analysis means, which allow the software analysis to adapt to the data provided by the docking stations and thus maximize the quality of the results obtained.
In a typical embodiment, the service center is a computer connected to the Internet to which a group of docking stations communicate. This service center may be part of the same organization that manages the monitoring instruments and docking stations, or it may be part of an external organization and may be located anywhere in the world. The communication between the docking station and the service center is also bi-directional. The docking station sends identification information about itself, the monitoring instrument""s location, time and date etc. It also sends exposure information, the user""s name and other information that is required or desired for record keeping. The service center can send software updates, new sensor configurations, requests for diagnostics, information or alerts for the user to be displayed on either the docking station of the monitoring instrument display. The communication between the docking station and the service center may occur at the same time as the instrument is being calibrated, if the docking station is connected to the Internet at that time. Alternatively, the docking station may include data storage means and simply store the information that needs to be sent to the service center until such time as a connection to the Internet is established. The means for sending data files over the Internet are well known in the art, and standard formats can be employed within the scope of this invention.
The docking station typically contains a bay into which the monitoring instrument can be connected. Alternative methods of communicatively coupling the monitoring instrument to the docking station include a cable connection, a jack connector, and an infrared link. Many other methods for transmitting electronic information between electronic devices are well known to those experienced in the art, and these can be substituted for the illustrations provided without limitation on the scope of this invention.
The functional role of the bay is to provide for bi-directional communication between the monitoring instrument and the docking station, and to provide means for the delivery of test mixtures of known composition for the purposes of calibrating and bump testing the monitoring instrument. Alternative mechanical and electrical configurations, which achieve this same result, can be used within the scope of this invention.
The term xe2x80x9cenvironmental monitoring instrumentxe2x80x9d is intended to apply to a wide variety of fixed and portable instruments, including gas detectors of various types, particulate matter detectors, liquid analysis instruments, and temperature and humidity recording devices. Also within the scope of the invention are devices for monitoring industrial processes.